Purification of phosphorus decasulfide (p4s10)

ABSTRACT

The present invention relates to a new and simple purification process of phosphorus decasulfide (P 4 S 10 ), also called phosphorus pentasulfide (P 2 S 5 ), which is used as thionating agent for the syntheses of various organic compounds, particularly the organic compounds having sulfur heteroatom(s).

TECHNICAL AREA

The present invention relates to a new and simple purification process of phosphorus decasulfide (P₄S₁₀), also called phosphorus pentasulfide (P₂S₅).

PREVIOUS TECHNIQUE

Nowadays, phosphorus decasulfide (P₄S₁₀) is widely used in industry and research labs, applications of which involve converting the carbonyl groups into thiones, formation of cyclic and heterocyclic systems and syntheses of sulfur containing organic compounds. Moreover, in industry, it is used in production of additives for lubricants and oil, syntheses insecticides, preparation of conducting and semiconducting materials having electronic and optoelectronic properties and syntheses of fire retardants.

In spite of its widespread use, reactivity of P₄S₁₀ is strongly dependent on its purity. If it is not pure enough, it has a strong smell of rotten-egg and gives low-yield or no-yield reactions. In some cases, impure P₄S₁₀ may yield a product totally different than the expected one.

Current purification techniques of P₄S₁₀, either in high or low levels, include distillation or soxhlet extraction with carbon disulfide (CS₂), which is toxic and has an extremely nasty smell. As these methods are difficult to perform, most of the available P₄S₁₀s are not pure enough

A Chinese patent (CN1887697) describes the purification of industrial P₄S₁₀ applying a simple distillation processes.

A Chinese patent (CN1887698) describes purification of industrial P₄S₁₀ applying a vacuum distillation method.

An USA patent (U.S. Pat. No. 5,283,042) describes a method for purification of white phosphorus.

SHORT DESCRIPTION OF THE INVENTION

The aim of the present invention is to provide a simple purification process of phosphorus decasulfide (P₄S₁₀). The process involves removal of impurities in P₄S₁₀ by taking advantage of rapid reactions of impurities with water compare with P₄S₁₀. This process is the best method available for the purification of P₄S₁₀.

DETAILED DESCRIPTION OF THE INVENTION

The method (100) for purifying diphosphorus pentasulfide (P₂S₅), also called tetraphosphorus decasulfide (P₄S₁₀) comprises the following steps;

-   -   Mixing tetraphosphorus decasulfide into an organic solvent by         addition (101),     -   Dropwise addition of water into the mixture of tetraphosphorus         decasulfide and the organic solvent until the color of the         mixture becomes light yellow, gray or white (102),     -   Mixing the mixture after the completion of water addition (103),     -   Filtering out the solid compounds in the mixed solution (104),     -   Drying the solid obtained by filtration (105)

In the method (100) subject to the invention, first tetraphosphorus decasulfide is admixed into an organic solvent (101). For the preferred realization of the invention, the addition operation is performed in a round bottom flask. For various applications of the invention, any organic solvents such as toluene, benzene, xylene, chlorobenzene, bromobenzene, dichlorobenzene, dibromobenzene, dichloromethane, chloroform, carbontetrachloride, dichloroethane, hexane, heptane, pentane, petroleum ether, diethyl ether, tetrahydrofuran, ethyl acetate, dioxane, pyridine, acetonitrile, acetone, triethyl amine, dimethyl formamide, dimethyl sulfoxide can be used. In other applications of the invention, at this step (101) the amount of tetraphosphorus decasulfide used can range from milligram to tone, while the amounts of organic solvents can be used within the range of milliliter to million liters.

Subsequently within method (100), water is dropwise added into the mixture of tetraphosphorus decasulfide and organic solvent until a pale yellow, gray or white color is reached (102). The volume of the added water can range from milliliter to million liters levels in different applications of the method. The step of adding water (102) can be performed between the temperatures of −90 (minus ninety) ° C. and the boiling point of the organic solvent employed. In the preferred embodiment of the invention, the step of adding water (102) is carried out at room temperature.

After the step of water addition (102), at a temperature between −90 (minus ninety) ° C. and the boiling point of the organic solvent used, the mixture is stirred (103) for about the desired duration (in a range of a few seconds up to hours) and the solid compounds in the stirred mixture are filtered (104). Filtration process (104) is performed either as simple filtration or as vacuum filtration in various applications of the method.

Within the method (100), the solid compound filtered out is dried and pure tetraphosphorus decasulfide is obtained (105). Drying step (105) of the present invention is achieved under either the atmospheric pressure or vacuum in different applications.

Using the method (100) it is possible to develop a wide variety of applications and the invention is not limited to the examples described herein and is essentially subject to the claims mentioned. 

1. A method (100) for the purification of diphosphorus pentasulfide (P₂S₅), also called tetraphosphorus decasulfide (P₄S₁₀) characterized by the following steps; Admixing tetraphosphorus decasulfide into an organic solvent (101) Dropwise addition of water to the mixture of tetraphosphorus decasulfide and organic solvent until pale yellow, gray or white color is reached (102) Mixing the solution after the completion of water addition (103) Filtration of the solid compounds from the mixture (104) Drying the solid compounds obtained by filtration (105)
 2. The method according to claim 1 characterized in that admixing tetraphosphorus decasulfide into an organic solvent (101) using a round bottom flask.
 3. The method according to claim 1 characterized in that the organic solvent (101) is selected from the group comprising toluene, benzene, xylene, chlorobenzene, bromobenzene, dichlorobenzene, dibromobenzene, dichloromethane, chloroform, carbontetrachloride, dichloroethane, hexane, heptane, pentane, petroleum ether, diethyl ether, tetrahydrofuran, ethyl acetate, dioxane, pyridine, acetonitrile, acetone, tri ethylene amine, dimethyl formamide, dimethyl sulfoxide.
 4. The method according to claim 1 characterized in that the step of dropwise water addition (102) into the mixture of tetraphosphorus decasulfide and organic solvent is performed at a temperature between −90 (minus ninety) ° C. and boiling point of the organic solvent employed.
 5. The method according to claim 1 characterized in that the step of dropwise water addition (102) into the mixture of tetraphosphorus decasulfide and organic solvent is preferably performed at room temperature.
 6. The method according to claim 1 characterized in that, the step of mixing/stirring the mixture (103) after the completion of water addition is performed at a temperature between −90 (minus ninety) ° C. and boiling point of the organic solvent employed.
 7. The method according to claim 1 characterized in that the step of filtration of solid compounds out of the stirred mixture (104) comprises simple filtration.
 8. The method according to claim 1 characterized in that the step of filtration of solid compounds out of the stirred mixture (104) comprises vacuum filtration.
 9. The method according to claim 1 characterized in that the step of drying the solid compounds filtered out (105), is performed at atmospheric pressure.
 10. The method according to claim 1 characterized in that the step of drying the solid compounds filtered out (105), is performed under vacuum. 